890 



DR. C. P. SONNTAG ON THE CLASSIFICATION 



character. Tomes (19) showed that the dental enamel in 

 Phascolomys possesses histological characters which sepai^ate it 

 from most, if not all Marsupialia, but he did not specifically 

 mention Phascolarctos. It appears, therefore, that in the dentition 

 we have an assemblage of characters bi-ought about by adaptation 

 and convergence, so they cannot be used to show a close affinity 

 between the Koala and Wombat. 



Generative Organs and Development : — ^In the Phascolarctidse 

 the vaginal culs-de-sac are separate, but they coalesce in some of 

 the Phalangeridfe, at least in Trichosurus (Eorbes). As regards 

 the fcetal membranes, Professor J. P. Hill informs me that they 

 are fundamentally the same, but differing in details, in the Koala 

 and Wombat. Moreover, the conditions in the Phascolarctidse 

 differ entirely from those in the Phalangeridse. 



Osteology : — I have compared the conditions in the material at 

 my disposal with Owen's account (8), and the essential points are 

 shown in the subjoined table : — 



Phascolarctidae. 



1. Pterygoid processes large. 



2. Intermaxillary bones increased trans- 



versely. 



3. Palatal process of maxilla forms a 



considerable part of boundary of 

 incisive foramina. 



4. Palatal foramina entirely on palate 



bones. 



5. Groove obsolete. 



6. Not ossified. 



7. Mid spongy bone simple *. 



8. Halves of mandible united. 



9. Seventh cervical vertebra perforated. 



10. Process beneatb the sixtb cervical 



process sliort. 



11. Anterior arch of the atlas partly 



cartilaginous. 



PhalangeridsE. 



1. Processes small. 



2. Bones not increased transversely. 



3. Maxillne form a small part of 



boundary. 



4. Palatal foramina extend into maxilla?. 



5. Groove runs from foramen rotundum 



to Gasserian fissure. 



6. Margin of tentorium ossified. 



7. Convolutions of mid spongy bone 



numerous and delicate. 



8. Halves separate. 



9. Not perforated. 



10. Process greatly expanded. 



11. Arch entirely osseous. 



In many of the osteological characters not included in the 

 above list there are differences in degree only in the Phalangers, 

 Phascolarctos, and Phascolomys. Doran has shown that the ear 

 ossicles of Phascolarctos differ entirely from those in the Phalan- 

 gerid.9e, but they have some points in common with those of 

 Phascolomys. 



B. Characters in lohich Phascolarctos and the Phalangeridce 

 differ from Phascolomys. 



External Characters :— In Phascolo')nys flaps of skin from the 

 lower lip protrude into the diastemata, but this is a new develop- 

 ment, associated, as in many Rodentia, with the type of dentition. 

 There is, however, no trace of these in the other animals. As 



* Owen's account is relied on here as the skulls in my possession are not perfect as 

 regards the turbinate bones. 



